ABSTRACT
In 1988, a new plasmid profile was observed for Vibrio salmonicida isolated from cod (Gadus morhua) and Atlantic salmon (Salmo salar) in fish farms in northern Norway. This new plasmid profile, which consisted of plasmids of 61, 21, 3.4, and 2.8 megadaltons, is 1 of 11 plasmid profiles which have so far been observed for V. salmonicida. Plasmid profiling and plasmid DNA hybridization were used in epidemiological studies of cold-water vibriosis. Our results indicate that V. salmonicida was transmitted from Atlantic salmon to cod and vice versa. The 61-megadalton plasmid was found exclusively in V. salmonicida strains originating from northern Norway, which is the only area in which this plasmid has ever been observed. Plasmid DNA hybridization and restriction endonuclease analysis show that the plasmid DNA of V. salmonicida remained stable throughout a 7-year survey.
Subject(s)
Fish Diseases/epidemiology , Plasmids , Vibrio Infections/veterinary , Vibrio/genetics , Animals , Cold Temperature , DNA Restriction Enzymes , DNA, Bacterial/genetics , Fish Diseases/microbiology , Norway/epidemiology , Nucleic Acid Hybridization , Salmon/microbiology , Species Specificity , Vibrio/isolation & purification , Vibrio Infections/epidemiology , Vibrio Infections/microbiologyABSTRACT
Yersinia ruckeri produces an antibacterial factor which inhibits the growth of a wide spectrum of Gram-negative and Gram-positive bacteria, though not other strains of Y. ruckeri. The antibacterial factor was produced at low temperatures (4-20 degrees C), but not at 37 degrees C. The activity was lost after treatment of the supernatant with chloroform, UV-light and after boiling of the supernatant. One did not succeed in obtaining the antibacterial factor in a sterile solution.
